import numpy as np

arr1d = np.array([1,2,3])
print("1维数组；")
print(arr1d)
print()

arr2d = np.array([[1,2],[3,4],[5,6]])
print("2维数组；")
print(arr2d)
print()

a=np.array([[1,2],[3,4]])
b=np.array([[4],[5]])
print(a @ b)